Angel Di Maria (Argentina)

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Argentina will start as big favourites to see off the challenge of Switzerland on Tuesday afternoon due to the presence of a certain Lionel Messi in their attack. However, midfielder Angel Di Maria will have an equally important role to play for the South Americans in Sao Paulo.

Di Maria is expected to once again line up on the left-hand side of a midfield three, with water carrier Javier Mascherano in the middle and Fernando Gago on the right of a 4-3-3 formation. This follows head coach Alejandro Sabella’s initial decision to experiment with playing three at the back in his side’s opening Group F win over Bosnia and Herzegovina.

And experienced Switzerland boss Ottmar Hitzfeld will be fully aware of the threat that Di Maria poses to his team, either when Argentina are on the attack or when his own side lose possession of the ball and the opposition are able to then counter at pace.

In both of those scenarios, it will be Di Maria whom Argentina’s players most look to in order to inject the necessary pace, width and creativity that will unsettle the Swiss back four. From there, the wide man then seeks to release one of the forward trio of Ezequiel Lavezzi, Messi and Gonzalo Higuain.

However, what makes the 26-year-old such a tricky customer to keep quiet is his impressive turn of speed, unbelievable work rate and seemingly uncanny ability to always pick out the right pass for a team-mate, similar in many ways to Netherlands winger Arjen Robben.

In fact, last season Di Maria registered a stunning 17 assists in La Liga for Real Madrid, more than any other player in Europe’s top five leagues. As Nick Miller said of the flyer in The Guardian:

His adaptability means he can ostensibly start from the left side of a midfield three but provide width when the instincts of the attacking three inevitably make them all drift into the middle, as well as giving some dynamism and flair to a midfield featuring the deeper-lying pair of Javier Mascherano and Fernando Gago. ...

... Di Maria has a licence to break forward and effectively become a fourth attacker but works hard enough to get back and cover when required.

And while the quick-footed Argentina international has not recorded an assist or a goal so far in his three matches at this summer’s tournament, do not be at all surprised if that statistic changes at the Arena Corinthians.

Xherdan Shaqiri (Switzerland)

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If Switzerland are to cause a shock by eliminating Argentina from the World Cup when the two countries meet on Tuesday, then their inspirational pint-sized forward Xherdan Shaqiri will have a starring role to play in Sao Paulo.

Shaqiri, who at just 169 centimetres is actually the same height as the opposition’s star man Lionel Messi—hence his nickname, "The Alpine Messi"—was in some doubt for the tournament after enduring an injury-ravaged club campaign with Bayern Munich last season. The 22-year-old suffered no fewer than three separate thigh problems, limiting him to just 17 Bundesliga appearances in his second season with the Bavarian giants.

However, judging by Shaqiri’s impressive displays in Group E—FIFA nominated him Man of the Match in both of the Swiss’ two victories­—that lack of game time at the Allianz Arena may actually now be benefitting both the player and his country. (Switzerland are in search of their first World Cup quarter-final since hosting the competition way back in 1954.)

It was Shaqiri’s outstanding performance in Switzerland’s final must-win group contest against Honduras, though, that will live long in the memory. In that match, the youngster scored only the second hat-trick at this summer’s World Cup.

And Shaqiri’s opening goal at the Arena Amazonia was yet further proof—if it were needed—of the Swiss starlet’s sensational long-range shooting abilities that first came to prominence when he scored his maiden international goal in a Euro 2012 qualifier against England in Basel four years ago.

As a result, Argentina will need to keep a close eye on someone whom The Independent’s Jack Pitt-Brooke described as a “stocky, punchy and skillful 22-year-old who can play anywhere across the front line.”

Lionel Messi (Argentina)

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All eyes on Tuesday will, as ever, be firmly fixed on Argentina captain Lionel Messi as his side attempt to make it through to the quarter-finals of the World Cup. If the forward carries on in the same breathtaking form that he has displayed so far in the tournament, then Switzerland could be in for a long afternoon in Sao Paulo.

Messi scored four goals in his country’s opening three Group F wins, including a brace last time out, as Sabella’s men saw off a brave challenge from Nigeria. The second of those goals was a stunning free-kick that prompted Super Eagles manager Stephen Keshi to claim that the playmaker "is from Jupiter."

However, there are concerns that Argentina, like with Diego Maradona in the past, are becoming too reliant on their inspirational skipper to continually dig them out of holes. (Messi also scored the winners against Bosnia and Herzegovina and Iran.)

Messi won three Man of the Match awards from FIFA in the group phase, so at least the 27-year-old is at last replicating his club form on the international stage. Sabella’s decision to make his star man captain now looks inspired after a recent run in front of goal that has seen Messi net a stunning 24 times for the South Americans in his last 24 internationals heading into the clash with the Swiss.

All of which is in stark contrast to how the diminutive attacker has often performed for his country in the past, especially during the 2011 Copa America on home soil. There, Messi’s limp performances were heavily criticised as the hosts crashed out on penalties to Uruguay.

But that has all been forgotten following the player’s memorable piece of individual brilliance against Bosnia and Herzegovina, followed by his stunning last-gasp curler that so deflated Iranian hearts. As Ed Malyon wrote in the Daily Mirror:

As a footballer and a sportsman, the current Argentine captain is on the cusp of overtaking the man whose legendary No.10 shirt he has finally filled.

As a teen, having moved to Barcelona, they said that young Leo could be the next Maradona. Future generations will search for the new Messi.

An Argentine fan’s banner on Wednesday featured the faces of the Argentine pontiff Francis, Maradona and Messi. Above them, it read: 'The Pope, God and the Messiah', hinting at divine intervention. ...

... With him in this form though, they can dream of the stars.

And Switzerland will need no reminding whatsoever about the threat that La Pulga poses to them. Messi scored his only international hat-trick ever in 2012, the last time the countries met in a friendly.

Thibaut Courtois (Belgium)

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Having a world-class goalkeeper in your ranks can often ultimately prove the difference between success and failure at the very highest level. With Thibaut Courtois between the sticks, Belgium must be quietly confident about their chances at this summer’s World Cup.

Marc Wilmots’ side let in just the one goal—from the penalty spot against Algeria—on the way to winning all three matches to top Group H and setting up a fascinating last-16 showdown against the U.S. in Salvador on Tuesday.

However, Wilmots will also be fully aware that far tougher challenges than Algeria, Russia and South Korea now await a team that, prior to the competition, many had predicted would be a force to be reckoned with at Brazil 2014. Those challenges begin with Jurgen Klinsmann and Co.

Equally, though, the U.S. will also know that getting past the imposing figure of the 6'6" Courtois will be no easy task, with the shot-stopper similar to former Germany and Bayern Munich No. 1 Oliver Kahn. The 22-year-old makes the goal appear so much smaller than it actually is.

The Chelsea custodian is also blessed with superb reflexes­—helped by his seemingly granite wrists—brilliant concentration levels and a calmness under pressure, and Courtois is impressive when dealing with the ball at his feet and crosses.

In all, then, the Belgium international appears to have virtually no obvious weaknesses to his game, as befits a player now universally recognised as the best young goalkeeper in the world. The Telegraph’s Alan Smith gave further credence to that here:

A very cool temperament helps to make Courtois what he is—one of the best goalkeepers around, universally admired as an outstanding talent. ...

... Courtois keeps his game nice and simple, staying in his box to reject the sweeper role adopted by the likes of France’s Hugo Lloris. He is also not one of those who always wants to be shouting at defenders in an effort to feel part of the proceedings. ...

... He naturally carries an unflappable air, similar in many ways to David Seaman.

And against the U.S. on Tuesday, Belgium’s youngest-ever keeper will have another chance to further cement his already burgeoning reputation as one of Planet Football’s brightest and best players in his position.

Tim Howard (USA)

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The U.S. may start as slight underdogs when they face Belgium in their last-16 tie in Salvador on Tuesday night. However, in goalkeeper Tim Howard, the Americans have a player who is currently at the peak of his powers, as they look to book a place in the last eight of the World Cup.

Howard, who will be winning his 104th cap when he lines up in goal against the Red Devils, has so far produced some remarkable saves to help Klinsmann’s side emerge from their group of death as runners-up to Germany and ahead of the likes of both Portugal and Ghana.

And as The Guardian’s Paolo Bandini noted of the custodian, who especially excels when it comes to his shot-stopping abilities: “Although yet to keep a clean sheet in Brazil, Howard has impressed in every appearance.”

In particular, Howard's double save to first deny Nani and then, after the winger’s effort had come back off the post, also somehow claw away Eder’s follow-up, defied belief in what was a Man of the Match display in his country’s 2-2 draw with Portugal that ultimately saw them through to the knockout phase of the tournament.

However, anyone who has watched Howard keep goal for the likes of Manchester United, Everton and the U.S. during the course of the past decade and more will not be surprised at all by the 35-year-old’s stellar performances to date at Brazil 2014.

And as Bandini went on to add about the player: “Howard rebounded to enjoy an excellent season at Everton leading into this World Cup, earning a contract extension through to 2018. If his athleticism has declined, then it is more than made up for by the leadership he brings to his teams.”

Consequently, you can be sure that Belgium internationals Marouane Fellaini, Kevin Mirallas and Romelu Lukaku—who have all played alongside Howard at Goodison Park—will have let their team-mates know in no uncertain terms about the size of the barrier that stands between them and a place in the last eight of the World Cup.

Eden Hazard (Belgium)

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Tuesday evening’s intriguing last-16 clash between Belgium and the U.S. looks like it will end up being an evenly contested affair in Salvador that could be decided by one moment of individual brilliance.

Who better to deliver that than the Red Devils’ star man, Eden Hazard?

Hazard, 23, has often struggled to reproduce his eye-catching club form of the past four years on the international stage. However, that has not been a problem so far at this summer’s World Cup for last season’s Young Player of the Year in England, with Hazard shining brightly for his country in their two opening Group H wins against Algeria and Russia.

In both of those matches, it was the little playmaker with the quick feet and unrivalled dribbling skills who was on hand to provide the assist for Belgium’s winning goal, much as Hazard also was on several occasions for his club last season.

In fact, so impressive was the wide man for the Blues in the previous campaign that manager Jose Mourinho even went as far as claiming on ESPN in February that Hazard was now "the finest young footballer in the world.”

Eden Hazard, 23, is vital to Belgium's hopes. Given licence to roam, Hazard plays across the final attacking third trying to open up the opposition with his intricate play. His clever runs can leave space for the likes of Kevin De Bruyne, Kevin Mirallas and Dries Mertens.

And against the U.S., do not be surprised at all if a tense, tight affair with few chances is settled by a moment of magic from the twinkle-toed Belgian.